1. What is BMI?

Body Mass Index (BMI) is a measure that uses height and weight to work out if a person's weight is healthy. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula adjusted for children:

Where:

• \( weight \) — Weight in kilograms
• \( height \) — Height in meters

Explanation: The result is compared against age- and sex-specific percentile charts to determine the weight category.

3. Importance of BMI Calculation for Kids

Details: Tracking BMI-for-age helps identify potential weight problems in children. Early identification allows for early intervention and healthy habit formation.

4. Using the Calculator

Tips: Enter weight in kg, height in meters, age in years (2-18), and select gender. For accurate results, measure height and weight without shoes and heavy clothing.

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI different for children than adults?
A: Children's body composition varies as they grow, so BMI must be interpreted relative to other children of the same age and sex.

Q2: What percentile ranges indicate overweight/obesity?
A: Generally, 85th-94th percentile = overweight; 95th+ percentile = obese. However, consult a healthcare provider for precise interpretation.

Q3: When should I be concerned about my child's BMI?
A: If BMI is consistently below 5th percentile or above 85th percentile, or if there are sudden changes in BMI trajectory.

Q4: Are there limitations to BMI for children?
A: BMI doesn't distinguish between muscle and fat, so athletic children may have higher BMI without excess fat.

Q5: Where can I find official UK growth charts?
A: The UK-WHO growth charts are available on the Royal College of Paediatrics and Child Health website.